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LHC Radio Frequency Swing . P. Baudrenghien AB/RF. Frequency Program for Synchrotrons. B is the guide field in T: 0.539 T to 8.386 T f inf = 400.789 662 MHz with h =35640 and 2 p R =26658.883m r is the bending radius r = 2784.32 m
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LHC Radio Frequency Swing P. Baudrenghien AB/RF
Frequency Program for Synchrotrons B is the guide field in T: 0.539 T to 8.386 T finf = 400.789 662 MHz with h=35640 and 2pR=26658.883m ris the bending radiusr = 2784.32 m E0 is the rest energy of the particle/ion being accelerated (in eV) q is the number of elementary charges in the particle/ion LHC conceptual design 1995 LEADE meeting
Proton acceleration We have: E0 = 938.26 x106 eV q = 1 The RF frequency ramps from 400.788 790 MHz at injection (0.539 T) to 400.789 658 MHz at top energy (8.386 T) N.B.: The bunch frequency @ 40 MHz is 1/10 times the above RF frequency. LEADE meeting
Ions Acceleration E0 = rest energy of ion = sum of energy of protons, neutrons (and electrons) minus binding energy q = number of protons (minus number of electrons) In all cases E0/q will be larger than the case of proton. Ions are less relativistic at injection and the frequency swing is larger. LEADE meeting
Lead ion acceleration For fully stripped lead Pb20882+we have: q = 82 (82 protons) E0 = 193.683 956 GeV considering the 82 p and 126 n with mp = 938.259 MeV, mn= 939.553 MeV and a binding energy of 7.87 MeV/nucleon E0/q= 2.362 x109 (to be compared to 0.93826 x 109 for protons) The RF frequency ramps from 400.784 139 MHz at injection (0.539 T) to 400.789 639 MHz at top energy (8.386 T) LEADE meeting
Other ions ? Considering only fully stripped ions: • for In11549+we getE0 = 107.08 GeV and E0/q= 2.185 x109 • for Kr8436+we getE0 = 78.215 GeV and E0/q= 2.173 x109 • for Ar4018+we getE0 = 37.24 GeV and E0/q= 2.069 x109 • for Sn12050+we getE0 = 111.74 GeV and E0/q= 2.235 x109 • for O168+we getE0 = 14.90 GeV and E0/q= 1.862 x109 In all cases the frequency swing is smaller than withPb20882+ (E0/q= 2.362 x109) N.B.: The above figures for E0 are approximations using the 7.87 MeV/nucleon figure for binding energy. Exact for Pb only. LEADE meeting
Remarks • In theory the frequency swing is not relevant to the experiment since you are only concerned by the RF during collisions • We do not guarantee any meaningful RF when no beam is in the machine (degaussing, access, shutdown,…) LEADE meeting